2. Field of the Invention
This invention pertains broadly to the field of digital communications. More particularly, the invention relates to an apparatus that discloses the error percentage or rate that a received digital data stream differs from its transmitted digital data stream.
2. Description of the Related Art
In the past, bit-error-rate (BER) measuring instruments or methods have been based on taking a large sample of a digital transmission over an extended period of time. During this time, transmitted bits were compared with received bits. Error pulses were counted for each received bit lacking correspondence with its transmitted bit. The number of errors was then divided by the total number of bits transmitted to give a BER measurement (i.e. the percentage of bits in error). This process took several minutes to tens of minutes or even longer just to obtain a single BER reading. Besides taking a long time, the measurements obtained were only the averaged values over the measurement period. Because of this averaging, moment-to-moment variations of BER or what is known in the art as the "burstiness" of the errors were not indicated.
There is a need in the digital communication field for a device that displays real-time BER instantaneously permitting one to observe how BER is changing with time.